1. Field of the Invention
The present invention relates to a charged particle beam writing apparatus and a charged particle beam writing method, and, for example, it relates to a writing apparatus and method that performs transmission processing of writing data at high speed.
2. Related Art
The microlithography technique which advances microminiaturization of semiconductor devices is extremely important as being a unique process whereby patterns are formed in the semiconductor manufacturing. In recent years, with high integration of LSI, the line width (critical dimension) required for semiconductor device circuits is decreasing year by year. In order to form a desired circuit pattern on semiconductor devices, a master or “original” pattern (also called a mask or a reticle) of high precision is needed. Thus, the electron beam writing technique, which intrinsically has excellent resolution, is used for producing such a highly precise master pattern.
FIG. 4 is a schematic diagram explaining operations of a variable-shaped electron beam (EB) writing apparatus. As shown in the figure, the variable-shaped electron beam writing apparatus operates as described below. A first aperture plate 410 has a quadrangular opening 411 for shaping an electron beam 330. A second aperture plate 420 has a variable-shape opening 421 for shaping the electron beam 330 having passed through the opening 411 of the first aperture plate 410 into a desired quadrangular shape. The electron beam 330 emitted from a charged particle source 430 and having passed through the opening 411 is deflected by a deflector to pass through a part of the variable-shape opening 421 of the second aperture plate 420, and thereby to irradiate a target workpiece or “sample” 340 placed on a stage which continuously moves in one predetermined direction (e.g. X direction) during the writing. In other words, a quadrangular shape that can pass through both the opening 411 and the variable-shape opening 421 is used for pattern writing in a writing region of the target workpiece 340 on the stage continuously moving in the X direction. This method of forming a given shape by letting beams pass through both the opening 411 of the first aperture plate 410 and the variable-shape opening 421 of the second aperture plate 420 is referred to as a variable shaped beam (VSB) method.
With the increase in integration of a pattern, a trend towards smaller pattern data to be written to a mask is progressing. When the trend of smaller pattern data progresses, consequently the data amount increases. Therefore, there is a problem that data transmission will be a factor of degrading the writing throughput.
It is conventionally performed that writing data input from outside the apparatus is divided per predetermined calculation region and allocated to a plurality of computers to perform data conversion processing in parallel in a plurality of computers in order to shorten processing time for data conversion (e.g., refer to Japanese Unexamined Patent Publication No. 2008-218767). Then, the data for which data conversion processing has been performed in parallel are collected, rearranged in order of writing, and transferred to a deflection control circuit.